Dual-purpose device for measuring rock permeability and soil-water characteristic curve

Abstract

The utility model discloses a dual-purpose device for measuring rock permeability and a soil-water characteristic curve. The dual-purpose device comprises a first pipeline, a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline which are communicated in sequence, the first pipeline is connected with the fourth pipeline through a confining pressure device; a first valve is arranged on the first pipeline; a second valve is arranged on the second pipeline, and a first pressure gauge is arranged between the second valve and the first valve; a third valve is arranged on the fourth pipeline; a second pressure gauge is arranged between the third valve and the confining pressure device; the fifth pipeline is respectively communicated with the humidification bottle and the third pipeline, and one side of the humidification bottle is connected with the inlet pipe; a capillary grid is arranged at the bottom of the confining pressure device, and a glass groove is formed below the capillary grid; the device can be used for measuring the rock permeability coefficient or the soil-water characteristic curve by controlling the opening or closing of the air valve and the disassembly and assembly of the capillary grating plate, and the measurement efficiency can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of geotechnical engineering, in particular to a dual-purpose device for measuring rock permeability and soil-water characteristic curve. Background Art

[0002] Currently, permeability and soil-water characteristic curve measurements are mostly conducted separately, using different experimental devices, and are mostly conducted on soil.

[0003] In nature, most rock seepage is unsaturated seepage. Rock permeability and soil-water characteristic curve are important hydraulic properties of rocks and are important parameters for studying unsaturated rock seepage. However, there is currently no soil-water characteristic curve measurement device for rocks. Traditional rock permeability measurement devices can only measure the permeability of saturated rock samples based on Darcy's law. General soil-water characteristic curve measurement methods have strict requirements on sample size or quality, making it difficult to prepare rock samples that meet the requirements, which limits the measurement of rock soil-water characteristic curves. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a dual-purpose device for measuring rock permeability and soil-water characteristic curve, which can measure both rock permeability and soil-water characteristic curve, thereby improving measurement efficiency.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: a dual-purpose device for measuring rock permeability and soil-water characteristic curve, comprising a first pipeline, a second pipeline, a third pipeline, a fourth pipeline and a fifth pipeline connected in sequence; the first pipeline is connected to the fourth pipeline through a confining pressure device; a first valve is provided on the first pipeline; a second valve is provided on the second pipeline, and a first pressure gauge is provided between the second valve and the first valve; a third valve is provided on the fourth pipeline, and a second pressure gauge is provided between the third valve and the confining pressure device; the fifth pipeline is respectively connected to the humidification bottle and the third pipeline, and one side of the humidification bottle is connected to the inlet pipe; a capillary grid is provided at the bottom of the confining pressure device, and a glass groove is provided below the capillary grid.

[0006] Preferably, the confining pressure device is a hollow cavity structure with an outer periphery being closed, and a circular through hole is provided at the top of the confining pressure device for docking with the first pipe, the top of the cylindrical rock sample inside the confining pressure device matches the circular through hole, and a circular through hole is provided at the bottom of the confining pressure device for matching the bottom of the cylindrical rock sample.

[0007] Preferably, the capillary grid is detachably connected to the circular through hole at the bottom of the confining pressure device.

[0008] Preferably, the glass tank is detachably connected to the circular through hole at the bottom of the confining pressure device.

[0009] Preferably, the top and side of the confining pressure device are detachably connected to the first pipe and the fourth pipe respectively.

[0010] Preferably, a fastener for limiting the position of the cylindrical rock sample is provided in the confining pressure device.

[0011] Preferably, the fastener includes two semicircular hoops, the inner sides of the two semicircular hoops are connected by bolts, and the outer sides of the semicircular hoops are detachably connected to the inner wall of the confining pressure device.

[0012] Preferably, a water outlet is provided on one side of the top of the glass tank.

[0013] Preferably, the first pipeline is arranged vertically, and the second pipeline and the fourth pipeline are arranged horizontally.

[0014] The beneficial effects of the utility model are as follows: the utility model can be used to measure the rock permeability coefficient or the soil-water characteristic curve by controlling the opening or closing of the air valve and the disassembly and assembly of the capillary grid plate; at the same time, it can improve the measurement efficiency, and the device can measure two basic parameters of rocks, and there is no need to operate the permeability coefficient and the pressure membrane instrument separately to measure the rocks separately; and after the permeability coefficient is measured, the rock sample is saturated with water, and the soil-water characteristic curve measurement can be directly continued, saving measurement time; its operation is simple, and when switching, it is only necessary to operate the switch of the pressure valve and the glass groove under the rock sample and install the capillary grid to change the original permeability coefficient measuring device into a pressure membrane instrument, and there is no need to disassemble and assemble too much equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The schematic diagram of a dual-purpose device for measuring rock permeability and soil-water characteristic curve is shown in FIG.

[0016] Figure 2 is a structural diagram of a fastener;

[0017] Figure 3 Schematic diagram of the structure of the glass tank;

[0018] In the figure, 1-confining pressure device, 2-fastener, 3-first valve, 4-capillary grid, 5-glass tank, 6-first pressure gauge, 7-second valve, 8-third valve, 9-second pressure gauge, 10-humidification bottle; 11-first pipeline; 12-second pipeline; 13-third pipeline; 14-fourth pipeline; 15-fifth pipeline. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1-3As shown, a dual-purpose device for measuring rock permeability and soil-water characteristic curve comprises a first pipe 11, a second pipe 12, a third pipe 13, a fourth pipe 14 and a fifth pipe 15 which are connected in sequence; the first pipe 11 is connected to the fourth pipe 14 via a confining pressure device 1; a first valve 3 is provided on the first pipe 11; a second valve 7 is provided on the second pipe 12, and a first pressure gauge 6 is provided between the second valve 7 and the first valve 3; a third valve 8 is provided on the fourth pipe 14, and a second pressure gauge 9 is provided between the third valve 8 and the confining pressure device 1; the fifth pipe 15 is respectively connected to a humidification bottle 10 and the third pipe 13, and one side of the humidification bottle 10 is connected to the inlet pipe; a capillary grid 4 is provided at the bottom of the confining pressure device 1, and a glass groove 5 is provided below the capillary grid 4.

[0021] Preferably, the confining pressure device 1 is a hollow cavity structure with an outer periphery being closed, and a circular through hole is provided at the top of the confining pressure device 1 for docking with the first pipe 11, the top of the cylindrical rock sample inside the confining pressure device 1 matches the circular through hole, and a circular through hole is provided at the bottom of the confining pressure device 1 for matching the bottom of the cylindrical rock sample.

[0022] Preferably, the capillary grid 4 is detachably connected to the circular through hole at the bottom of the confining pressure device 1 .

[0023] Preferably, the glass tank 5 is detachably connected to the circular through hole at the bottom of the confining pressure device 1 .

[0024] Preferably, the top and side of the confining pressure device 1 are detachably connected to the first pipe 11 and the fourth pipe 14 respectively.

[0025] Preferably, a fastener 2 for limiting the position of the cylindrical rock sample is provided in the confining pressure device 1 .

[0026] Preferably, the fastener 2 includes two semicircular hoops, the inner sides of the two semicircular hoops are connected by bolts, and the outer sides of the semicircular hoops are detachably connected to the inner wall of the confining pressure device 1.

[0027] Preferably, a water outlet is provided on one side of the top of the glass tank 5 .

[0028] Preferably, the first pipeline 11 is arranged vertically, and the second pipeline 12 and the fourth pipeline 14 are arranged horizontally.

[0029] In the above technical solution, a multi-pipeline setting ensures that fluids (such as water or gas) can flow smoothly and orderly in the device; by adjusting the valves and connection configurations on different pipelines, the device can be flexibly used to measure the permeability of rocks and the soil-water characteristic curve of soil, realizing the diversification of measurement functions.

[0030] In the above technical solution, second valve 7 is used to control the flow of gas or liquid in second pipe 12, and first pressure gauge 6 is used to monitor pressure changes in second pipe 12 in real time. By adjusting second valve 7, precise control of the flow direction of gas or liquid can be achieved. The reading of first pressure gauge 6 helps monitor pressure changes during the experiment and provides an important basis for data analysis.

[0031] A third valve 8 is provided on the fourth pipeline 14 , and a second pressure gauge 9 is provided between the third valve 8 and the confining pressure device 1 ; the reading of the second pressure gauge 9 reflects the change of the internal pressure of the fourth pipeline 14 .

[0032] The fifth pipe 15 and the dehumidification bottle 10 allow for convenient adjustment of the system's internal humidity or injection of specific fluids into rock or soil samples to simulate underground environments or conduct specific experimental treatments. This is particularly important for measuring soil-water characteristic curves, as the soil's moisture content must be controlled to observe its moisture absorption and dehydration processes.

[0033] A capillary grid 4 is provided at the bottom of the confining pressure device 1. The capillary grid 4 can provide a close hydraulic connection between the rock sample water phase and the external water phase, reduce the capillary end effect to prevent the gas phase from flowing through it, and accurately collect water volume.

[0034] The working principle of this utility model is:

[0035] (1) Saturation permeability measurement process:

[0036] Remove the capillary grid 4, place the rock sample into the confining pressure device 1, and use the fastener 2 to clamp the top of the rock sample radially. At the same time, tightly connect the top of the rock sample to the first pipe 11 in the axial direction, and tightly connect the bottom of the rock sample to the circular through hole at the bottom of the confining pressure device 1. Open the first valve 3 and the second valve 7. At this time, the upper and lower surfaces of the rock sample are both under atmospheric pressure. Open the third valve 8 and close the second valve 7. Use the inlet pipe on one side of the dehumidification bottle 10 to introduce gas, and then ventilate the interior of the confining pressure device 1 through the fifth pipe 15 and the fourth pipe 14. Read the confining pressure value through the second pressure gauge 9. When the required confining pressure value is reached, close the third valve 8. Then, inject water to carry out the constant head permeability test:

[0037] Darcy's law, also known as the linear seepage law, describes the linear relationship between the seepage velocity and hydraulic gradient of water in saturated soil. The seepage rate Q is proportional to the upstream and downstream head difference (h2-h1) and the cross-sectional area A perpendicular to the direction of water flow, and inversely proportional to the seepage length L, that is:

[0038] ;

[0039] Where Q is the seepage rate per unit time; K is the permeability coefficient, which is equal to the seepage velocity of water when the hydraulic gradient is 1, cm / s.

[0040] Using the above-mentioned Darcy's law principle, the length L of the rock, the constant head Δh, and the cross-sectional area A of the rock are known, and water injection is used to maintain a stable water head. Specifically, the capillary grid 4 is installed, the first valve 3 and the second valve 7 are opened, and water is introduced through the inlet pipe on one side of the tidal bottle 10. Then, water is introduced into the vertically arranged first pipe 11 through the fifth pipe 15 and the second pipe 12. The first valve 3 is in the open state, and water overflows from here, so that the liquid level in the first pipe 11 is constant, thereby maintaining a certain water head. Water penetrates through the rock sample from top to bottom. At this time, the side of the rock sample is under a certain confining pressure. The infiltrated water flows out from the circular through-hole at the bottom of the confining pressure device 1 and the capillary grid 4 and enters the glass tank 5. The timer starts when the water flows steadily into the measuring cylinder from the water outlet on the top side of the glass tank 5 (the measuring cylinder is placed on the side of the water outlet of the glass tank 5, not shown in the figure). The measuring cylinder measures the amount of water V flowing through the sample within a certain time t, then ;

[0041] According to Darcy's law: ;

[0042] Combining the above two equations, we get: ;

[0043] The rock permeability coefficient can be measured by measuring the water output and knowing parameters such as rock dimensions and the constant head of the device. Permeability indicates the rate of water migration through soil, expressed as the thickness of water permeating the surface per unit time. The unit is mm / h. The conversion relationship between permeability coefficient (cm / s) and permeability (mm / h) is permeability = 3600 / permeability coefficient. This relationship can be used to calculate permeability.

[0044] (2) Soil-water characteristic curve (matrix suction-saturation curve) measurement process:

[0045] After the saturated permeability measurement is complete, the bottom of the first pipe 11 is separated from the top of the confining pressure device 1, the water inside is drained, and the device is reinstalled. The first valve 3 is closed, and the second valve 7 is opened. Gas is introduced through the inlet tube on the side of the dehumidification bottle 10, and then through the fifth pipe 15 and the second pipe 12 into the vertically arranged first pipe 11. The capillary grid 4 provides a close hydraulic connection between the rock sample's aqueous phase and the external aqueous phase, reducing the capillary end effect that prevents gas from flowing through it, allowing for accurate estimation of the water volume. After gas injection, the second valve 7 is closed. The air pressure in the enclosed space reaches a certain value. The change in the water volume in the graduated cylinder is observed at regular intervals. When the water volume no longer changes, according to the principle of pressure equilibrium, the matric suction equals the pressure value. After opening the first valve 3 to restore atmospheric pressure, the rock sample is removed and weighed using a balance. The rock saturation is converted to obtain a set of matric suction-saturation relationships. Repeat the experiment to obtain a matric suction-saturation curve.

[0046] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A dual-purpose device for measuring rock permeability and soil-water characteristic curve, comprising a first pipe (11), a second pipe (12), a third pipe (13), a fourth pipe (14) and a fifth pipe (15) connected in sequence; characterized in that: The first pipeline (11) is connected to the fourth pipeline (14) through the confining pressure device (1); a first valve (3) is provided on the first pipeline (11); a second valve (7) is provided on the second pipeline (12), and a first pressure gauge (6) is provided between the second valve (7) and the first valve (3); a third valve (8) is provided on the fourth pipeline (14), and a second pressure gauge (9) is provided between the third valve (8) and the confining pressure device (1); the fifth pipeline (15) is communicated with the humidification bottle (10) and the third pipeline (13) respectively, and one side of the humidification bottle (10) is connected to the inlet pipe; a capillary grid (4) is provided at the bottom of the confining pressure device (1), and a glass groove (5) is provided below the capillary grid (4).

2. A dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 1, characterized in that: The confining pressure device (1) is a hollow cavity structure with an outer closed portion, and a circular through hole is provided on the top of the confining pressure device (1) for docking with the first pipe (11), the top of the cylindrical rock sample inside the confining pressure device (1) matches the circular through hole, and a circular through hole is provided on the bottom of the confining pressure device (1) for matching the bottom of the cylindrical rock sample.

3. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 2, characterized in that: The capillary grid (4) is detachably connected to the circular through hole at the bottom of the confining pressure device (1).

4. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 2, characterized in that: The glass tank (5) is detachably connected to the circular through hole at the bottom of the confining pressure device (1).

5. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 2, characterized in that: The top and side of the confining pressure device (1) are detachably connected to the first pipe (11) and the fourth pipe (14), respectively.

6. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 1, characterized in that: The confining pressure device (1) is provided with a fastener (2) for limiting the position of the cylindrical rock sample.

7. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 6, characterized in that: The fastener (2) comprises two semicircular hoops, the inner sides of the two semicircular hoops are connected by bolts, and the outer sides of the semicircular hoops are detachably connected to the inner wall of the confining pressure device (1).

8. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 1, characterized in that: A water outlet is provided on one side of the top of the glass tank (5).

9. The dual-purpose device for measuring rock permeability and soil-water characteristic curve according to claim 1, characterized in that: The first pipeline (11) is arranged vertically, and the second pipeline (12) and the fourth pipeline (14) are arranged horizontally.

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